Desulfurization of hydrocarbons with a mixture of a group viii metal and group viii metal oxide or sulfide



United States Patent A'MIXTURE- oFA GROUP'VIII'METAL AND new rm M rALam, R U F D Archibald P. Stuart, Media, Pa., assignor to Sun OilCompany, Philadelphia, Pa., a corporation of New Jersey No Drawing.Filed Apr. 9, 1957, Ser. No. 651,587 11 Claims. (Cl. 208-244) Thisinvention relates to the separation of sulfur compounds from petroleum,and more particularly to the use of special adsorbent material in orderto accomplish such separation.

It is often desirable to separate sulfur compounds from petroleumfractions in which they normally occur. Thus, mercaptans may be removedfrom light fractions such as gasoline to eliminate undesirable odor andimprove lead susceptibility. In the case of fuel oil, it is oftendesirable to remove mercaptans and other sulfur compounds in order tomeet specifications as to sulfur content. Sulfur compounds may beremoved from charge stocks for cat- 'alyt'icreforming processesemploying platinum-containing catalyst, in order to avoid undesirableeffects of ex,-

cessive amounts of sulfur on the catalyst.

"In the case of lubricating oils, sulfur compounds can be separatedtherefrom in order to obtain sulfur concent'r'ates which have valuableproperties as anti-oxidants fof various petroleum fractions. It would bedesirable to obtain a greater extent of sulfur removal and greaterconcentration of sulfur in the removed material than are obtainable withprior art methods of obtaining such concentrates. t i

The process according to'the present invention provides a highlyeffective manner of separating sulfur compounds from petroleum. Theprocess is capable of being carried out at relatively lowtemperatures,for example in theappro'ximate'rang'e from 50 F.-to 300- F.The adsorbent material which is employed can be revivified for re-use bycontact of the adsorbent with a desorbent liquid.

The process of the present invention involves; in'one embodiment, firstcontacting petroleum material in liquid phase With a solid porousadsorbent intimately associated with a 'group VlTI metal. It has beenfound thatthe presence ofthe group VIII metal promotes the selectiveadsorption of sulfur compounds. This permits a desulfurized hydrocarbonfraction to be obtained which'has a low sulfur content and is obtainedin good yield. It also permits a sulfur concentrate to"be'obtaine'd'which has only a relatively small amount of hydrocarbon materialassociated therewith.

Group VIII metals generally are suitable for use inpreparing thedesulfurizing agent. Nickel vis a preferred metal for such use, butothers suchas cobalt, iron, plati: num, palladium, rhodium, etc. canalso be employed.

By use of a desorbent liquid, it is possible to first desorb thehydrocarbon materials from the absorbent, and subsequentlydesorb sulfurcompounds remaining on the adsorbent after the desorption ofhydrocarbons. Usually, the amount of sulfur compoundsjdesorbed will bewithin the approximate range from 80 to 100 percent of thesul furcompounds in the charge. If desired, the desorption of hydrocarbons canbe performed in stages, obtaining firsta fraction which is relativelyconcentrated with regard to saturated hydrocarbons (refractive index 11about 1.46 to 1.50), then a mononuclear hydrocarbon concentrate (n about1.50 to 1.54), then a dinuclear 2,951,034 Patented Aug. 30, 196Q ICE . 2aromatic hydrocarbon concentrate (r1 2 about 1.54 to 1.59), and soforth. In this type of, operation, hydrocarbon fractions are obtainedwhich, in, addition to being desulfurized, are improved for subsequentuse as a result of change in their hydrocarbon composition.

Thus, for example, a saturated hydrocarbon material obtained in thedesorption generally has improved properties, in the case ofalubricating oil, with regard to viscosity index, or improved propertiesfor use as a charge stock in a catalytic cracking as a result of removalof aromatic hydrocarbons therefrom. The automatic hydrocarbonconcentrate obtained in'the desorption generally has improved propertiesfor use as rubber processing oil or as -oil to be employed in themanufacture of carbon black. a

The absorbent material which is employed as desulfurizing agentcomprises in apreferred embodiment a porous adsorbent and a group VIIImetal in, intimate association. Any suitable manner ofobtaining-intimate association of the group VIII metal and the porousadsorbent can be employed in this embodiment. For example, the porousadsorbent in-granular form can be impregnated'with an aqueous solutionof a salt containing the metal in question, e.g. nickelnitrate, achloroplatinate salt, etc; the impregnated adsorbentis then dried,calcined and reduced by contacting with hydrogen, thereby to obtain anadsorbent having the metal contained in the pores thereof. Anothersuitable manner of preparation involves forming, a paste containingintimately admixed finely divided porous adsorbent and fine particles ofthe metal, and extruding the paste to obtain particles com prising theadsorbent and metalin intimate association.

In a preferred embodiment, the desulfiurizing agent comprises apartiallyv oxidized or partially sulfided group VIII metal. It isbelieved that partial oxidation or sulfidation forms' metal oxide ormetal sulfide at the most active sites of the metal, leaving the lessactive sites in the free metal state. The less active sites aresufficiently active to provide good adsorption of. sulfur compounds, butnot so active as to make it difficult or impossible to desorb the sulfurcompounds. Thus, a more satisfactory adsorption-desorption operation isobtained than in the case wherethe'metalis not partially oxidized orsulfided, and where sulfur compounds'are too strongly adsorbed at themost activesitesto be readily desorbed. In this embodiment, theweightratio of free metal to metal oxide or sulfide-is preferably in' the,approximate t ee 09 m r i fe ab rltl; .1 2.4;1;

' The P i l a da iseq sulfide/ 911 s i be ref rmed in any'suitablemanner, preferably by eorrtagting the nietalwith oxygen or a"sulfurcorrtaining material, eg.

Part of the metal a f h lasidsi 9 E lfi l P o h metal remaining inil l en onfine j ta Instea of proceeding from theuncombined state .to thepartially oxidized or sulfurized state, one can proceed frorn thecombined state and convert part of the metal compound to the metallicstate, cg. bypartial reduetionpf the metal oxide, part ofthe metalremairriug in the com binedstate. Mixtures of metal andmetaloxide orsulfur are kndwfi. e a a 1 .9 and in flie -light qfthe P spscifisafion-aP r ian sk l ed t e a isen. s leq suitable procedure'for preparing suchmixtures. Q

A particularly good-'desulfurizing adsorbent for use according to theinvention is one comprising metallic nickel, nickel Oxide or lfide. andamorous ads ben the total nickel content of the desu lfuri zingagentbeing within the approximate range, from 50 to 7 5 weight percent. I 30to 60 weight percent. of thefdes llf rigipg agent in this embodimentcomprises metallic niolgel, land 20 to 45. gh P e qmpusesni sel; qxisi gnic sel Sulfide or a xt re s sl oxide ani kel s lfide It has been foundthat this desulfurizing agent provides particularly good selectiveadsorption of sulfur compounds.

The desulfurizing agent employed according to the inventionpreferablycomprises a porous adsorbent in intimate association with thegroup VIII metal. However, it is also within the scope of the inventionto use an agent, such as partially oxidized Raney nickel, which does notcontain a separate porous adsorbent. Where a porous solid adsorbent isused, any such adsorbent can be employed. Such adsorbents are well knownin the art as a class and include such materials as silica, gel,alumina, kieselguhr, bauxite, silica-alumina composites, fullers earth,pumice, clays, etc. In this embodiment, the metal is preferablypartially oxidized or sulfided, though the metal can be substantiallyentirely in the uncombined state.

The desulfurizing agent according to the invention can be prepared forexample by impregnating silica gel particles with aqueous nickel nitratesolution, drying the impregnated gel at 260 F., calcining at 800 F. toconvert nickel nitrate to nickel oxide, and partially reducing at 800 F.with hydrogen and steam. If desired, the nickel can be reducedsubstantially entirely to the metallic state and then re-oxidized toconvert part of the nickel to the oxide. Another illustrativepreparation of the desulfurizing agent involves impregnation of anadsorbent with ammonium chloroplatinate solution followed by slow dryingand heat decomposition of the deposited salt. Any other suitable mannerof preparation can be employed, which produces an intimate associationof the adsorbent with a group VIII metal.

Any suitable desorbent liquid can be employed to remove hydrocarbons andsulfur compounds from the adsorbent. It is known in the art to performvarious separations of mixtures of material by adsorption-desorptiontechnique, wherein a porous solid adsorbent is first contacted with thematerial to be separated in liquid phase and then with a desorbentliquid to selectively remove certain of the materials adsorbed on theadsorbent. Materials which can be employed as desorbent liquids in suchprocessing are well known in the art and include such compounds asn-pentane, benzene, ethanol, isopropanol, thiophene, etc. Any of theknown desorbent liquids can be employed in the process according to theinvention. Examples of suitable desorbent liquids are disclosed inUnited States Patent No. 2,585,490, issued February 12, 1952, to I. L.Olsen. A plurality of desorbent liquids having increasing polarity canbe employed in series if desired to remove successively the morestrongly adsorbed components of the charge stocks.

In one embodiment, the charge oil, prior to contacting with thedesulfurizing agent according to the invention, is given a pretreatmentin order to remove therefrom the most strongly adsorbable sulfurcompounds therein. These compounds may constitute for example about 1 to15 percent of the total sulfur compounds in the charge. If these sulfurcompounds are not previously removed, they may remain on thedesulfurizing agent in the subsequent step since they are sometimesdifi'icult to remove by ordinary desorption technique. By removing themin a pretreatment, it is possible to obtain operation in whichsubstantially all of the sulfur compounds can be desorbed from thedesulfurizing agent, and the latter re-used many times. Any suitablemanner of removing the most strongly adsorbable sulfur compounds can beemployed in the pretreating step. Thus, for example, the pretreatmentcan involve contacting the charge oil with a separate portion of thesame adsorbent which is employed in the subsequent step or with someother adsorbent such as clay. Treatment with concentrated sulfuric acid.can also be employed to remove the most strongly adsorbable sulfurcompounds. The desirability of the pretreatment will depend on thenature of the charge, and in some instances at least pretreatment willnot be necessary.

The process of the invention can be applied to petroleum fractionsgenerally such as gasoline, naphtha,

5 kerosene, fuel oil, lubricating oil, etc. Straight run or crackedfractions can be treated.

If desired, the contacting according to the invention can be performedin such manner that selective adsorption of sulfur compounds on theadsorbent is chtained, the hydrocarbon product being obtained aseffluent from the adsorbent bed in the initial contacting, and thesulfur compounds remaining on the adsorbent being subsequently desorbedto obtain a single desorbed fraction. Preferably, however, the processis performed 5 in such manner that a plurality of desorbed fractions areobtained, including a desulfurized hydrocarbon fraction or fractions andsubsequently a sulfur concentrate or concentrates.

The following example illustrates the invention:

The charge oil was a lubricating oil distillate derived from naphthenicbase crude and having the following typical properties: specific gravityd of 0.9340, refractive index 11 of 1.5153, Saybolt Universal viscosityat 100 F. of 603 seconds and at 210 F. of 55 seconds, and sulfur contentof 0.26 weight percent.

The desulfurizing agent was a mixture of nickel and nickel oxide inintimate association with kieselguhr and had the following composition:nickel 43.6%, nickel oxide 28.2%, silica 19.9%, alumina 3.0% andgraphite 4.0%. One-eighth inch pellets were crushed to a powder in anitrogen atmosphere. 500 grams of the powder were placed in a column toprovide a 4 foot packed section.

A solution of 25 grams :of the charge oil in 50 ml. of n-pentane wasintroduced into the bed of desulfurizing agent. The following desorbentswere used in series: 1450 ml. of 4% benzene in pentane, 1050 ml. of 10%benzene in pentane, 900 ml. of 24% benzene in pentane and 2000 ml. of 7%isopropanol in benzene. Effluent cuts were taken, desorbent strippedtherefrom and the cuts composited into the fractions shown in thefollowing table. Fraction 1 contained the first 10.6% of effluent oil,Fraction 2 the next 19.9%, and so' forth. The sulfur content of eachcomposite fraction is shown, also the 45 cumulative weight percent ofsulfur, based on total charge oil, contained in the efiiuent oil. Thus,Fraction 2 contained about 0.002% sulfur based on total charge, Fraction3 about 0.003%, and so forth.

ft Wt ri a we tive Fraction Desorbent Wt. Percent Wt.

Percent Sulfur Percent O Sulfur l0. 6 0 30. 5 0.01 0. 002 47. 0 0. 02 0.005 54. 3 0. 03 0. 007 61. 5 0. 04 0. 010 66. 5 0. 08 0. 014 76. 6 0. 110. 025 84. 8 0. 3 0. 050 90. 4 0. 57 0. 082 94. 5 1. 05 0. 125 24%benzene in n-pentane. 98.0 1. 86 0.208 12 7% lsopropanel in benzene. 99.0 1. 86 0. 227

These results show that the first 90 percent of efiiuent contained about0.082/ 0.26, or about 31.6 percent of the sulfur in the charge stock,representing about 68.4 percent desulfurization of 90 percent of theoil. In other werk, up to about 75 percent desulfurization of 90 percentof the charge was obtained. The total recovery of sulfur in desorbedfractions was about 0.277/0.26, or about 87 percent.

By way of contrast, only about 37 percent of the sulfur in the chargecouldberecovered in desorbed fractions from Raney nickel usingdesorption technique essentially the same as that employed with thenickel-nickel oxide-kieselguhr adsorbent.

In the desorption of oil from the nickel-nickel oxidekieselguhradsorbent, the refractive index of the efliuent oil increased steadilyfrom about 1.48 for the first desorbed fraction to about 1.51 forFraction 5 and to 1.6 at about Fraction 9, then decreased to about 1.58at about Fraction 11, and rose again to about 1.59 at about Fraction 12.

In the preceding example, a plurality of desorbents having increasingpolarity were employed in order to obtain a large number of desorbedfractions having gradually changing properties. It is to be understoodthat the entire desorption can if desired be performed with a singledesorbing agent having constant composition, or with two desorbingagents in series, the latter having greater polarity, etc.

Thus, for example, 1000 ml. of 24% benzene in pentane is used in oneembodiment as the sole desorbent, and a separation of sulfur compoundsfrom hydrocarbons comparable to that disclosed previously is obtained.The sulfur compounds are in one embodiment desorbed in later portions ofthe same desorbent. In another embodiment, they are desorbed primarilywith another desorbent having greater polarity, e.g. benzene, alcohol,mixtures of benzene and alcohol, etc.

Generally similar results, with regard to efficiency of sulfurseparation, to those obtained in the above example, are obtained whentreating other petroleum fractions such as gasoline, fuel oil, etc.Other group VIII metals can be employed in place of nickel.

The adsorption stage is preferably performed at relatively lowtemperature, e.g. 50 F. to 150 F., though higher temperatures, e.g. upto 300 F. or higher, can be employed if desired. The desorption stagecan also be performed at relatively low temperature, e.g. 50 F. to 150F., though higher temperatures, e.g. up to 300 F. or higher, favordesorption efliciency.

The process according to the invention provides in various embodimentsnew and improved manners of desulfurizing petroleum, reactivating thedesulfurizing agent for re-use, recovering sulfur concentrates frompetroleum,

and separating petroleum into fractions having different hydrocarboncomposition. The sulfur concentrates obtained from various types ofpetroleum charge stocks in certain embodiments can be employed for anyof the known uses of such concentrates.

The invention claimed is:

1. Process for removing sulfur compounds from petroleum hydrocarbonswhich comprises: contacting petroleum hydrocarbons in liquid phase at atemperature within the approximate range from 50 F. to 300 F. with adesulfurizing agent comprising a group VHI metal and a compound selectedfrom the group consisting of an oxide and a sulfide of a group VIIImetal, and contacting said agent with a desorbent liquid, thereby todesorb sulfur compounds.

2. Process for removing sulfur compounds from petroleum hydrocarbonswhich comprises: contacting petroleum hydrocarbons in liquid phase at atemperature within the approximate range from 50 F. to 300 F. with adesulfurizing agent comprising about to 60 weight percent of metallicnickel and about 20 to 45 weight percent of a compound selected from thegroup consisting of nickel oxide and nickel sulfide.

3. Process for removing sulfur compounds from petroleum hydrocarbonswhich comprises: contacting petroleum hydrocarbons containing sulfurcompounds in liquid phase with a porous adsorbent in intimateassociation with a group VIII metal, thereby to adsorb sulfur compounds;and contacting said adsorbent with a desorbent liquid, thereby to desorbsulfur compounds.

4. Process according to claim 3 wherein said adsorbent containingadsorbed hydrocarbons and sulfur compounds is first contacted with adesorbent liquid to selectively desorb hydrocarbons and recover a firsteffluent containing hydrocarbons having reduced sulfur content, and isthen contacted with a desorbent liquid to desorb a sulfur compoundconcentrate.

5. Process according to claim 1 wherein said petroleum hydrocarbonsconstitute a lubricating oil fraction.

6. Process according to claim 3 wherein said petroleum hydrocarbonsconstitute a lubricating oil fraction.

7. Process according to claim 1 wherein said agent is prepared bypartially oxidizing saidmetal.

8. Process according to claim 1 wherein said agent is prepared bypartially sulfiding said metal.

9. Process according to claim 1 wherein said temperature is within theapproximate range from 50 F. to F.

10. Process according to claim 2 wherein said agent consists essentiallyof metallic nickel and nickel oxide.

11. Process according to claim 2 wherein said agent constitutessubstantially the sole contacting agent.

References Cited in the file of this patent UNITED STATES PATENTS809,087 Blackmore Jan. 2, 1906 1,944,170 Darlington Jan. 23, 1934-2,073,578 Gwynn Mar. 9, 1937 2,273,298 Szayna Feb. 17, 1942 2,306,933Burk Dec. 29, 1942 2,337,358 Szayna Dec. 21, 1943 2,559,323 SpillaneJuly 3, 1951 2.756,182 Kimberlin et a1 July 24, 1956

1. PROCESS FOR REMOVING SULFUR COMPOUNDS FROM PETROLEUM HYDROCARBONSWHICH COMPRISES: CONTACTING PETROLEUM HYDROCARBONS IN LIQUID PHASE AT ATEMPERATURE WITHIN THE APPROXIMATE RANGE FROM 50*F. TO 300*F. WITH ADESULFURIZING AGENT COMPRISING A GROUP VIII METAL AND A COMPOUNDSELECTED FROM THE GROUP CONSISTING OF AN OXIDE AND A SULFIDE OF A GROUPVIII METAL, AND CONTACTING SAID AGENT WITH A DESORBENT LIQUID, THEREBYTO DESORB SULFUR COMPOUNDS.